The present invention relates to saws, particularly to saws for cutting wafers for optical and electronic applications, for example, and more particularly to a hydrodynamic blade guide or bearing for a saw which retains the saw blade centered in the saw kerf.
Cutting or slicing of materials, such as those utilized in optical and electronic applications, as well as ceramics, glass, and brittle composite material is an expensive process and generally results in damaged, non-smooth, and non-flat surfaces. Substantial effort has been directed to resolve the problems associated with cutting of such materials.
Materials from which wafers are cut include optical and electronic materials in boule form such as KDP, GaAs, and silicon, as well as other brittle materials. The initial operation in manufacturing wafers from boules is the slicing or cutting process. Slicing currently suffers from its inability to produce flat surfaces free from sub-surface damage while maintaining long saw blade life and small saw kerf. The significant penalty associated with this slicing process derives not just from the cost of the sawing operation but also from the cost of subsequent processes to remove damage and to planarize the surface which are made necessary by the sawing or slicing operation. In addition, not only do the above-described slicing or cutting problems come into play, but also the cost of wasted materials lost to the saw kerf must be considered. The smaller the kerf, the greater the number of usable wafers cut from a boule.
Thus, there has been a need for a means or method by which slicing of boules, for example, can be effectively and efficiently carried out. This need is satisfied by the present invention, which utilizes a self-pumped hydrodynamic blade guide or bearing which functions to maintain the saw blade centered in the saw kerf in the workpiece. The blade guide or bearing utilizes relieved pockets or grooves on the sides of the saw blade which entrain cutting fluid, and the saw kerf in the workpiece itself provides the stator surface, whereby the trapped fluid provides pressure between the blade and the workpiece as an inverse function of the gaps between the blade surface and the workpiece surface, which results in maintaining the saw blade centered in the saw kerf.